This machine's is I5 7400 so that it ought to support NVME SSD natively.Although it hasn't M.2 Interface,we still can use adapter card pluging in the PCIE slot.But I had set all I could do in the bios but it still couldn't show anything about the NVME SSD in the boot list.So now I could just use the "clover" to launch the system in NVME SSD instead.I think maybe something lacking in the bios,so I put the bios I dumped in this machine.Btw,There is no csmcore or cpudxe(nearly blank I saw in mmtools) in this bios(It occured in some intel mobos bios too),and how to add the nvme module in this type of bios?Very thank!!!

CSMCore has nothing to do with NVME BIOS Mod? Add NVME Module at end of main BIOS volume (the one you see in UEFITool with all the "DXE" entries) after last DXE in that volume. This volume can also be found on Intel by searching for BIOS Lock (Unicode), or by finding the setup module, or AMITSE module in many BIOS, that would be the volume you put it into.Speaking in general, I have not looked at the BIOS you attached yet

Here is your mod BIOS, make sure you check with MEInfoWin.exe -verbose And make sure at the end of report Measured & Verified boot are not enabled on the left/FPF side, if they are you cannot use mod BIOShttp://www.filedropper.com/dell3669-nvme

If you dumped this with FPT, only flash it back with FPT. Because if this board has two BIOS chips this may need split and flashed into both chips (Some Dell like that, some only single and I don't know how you dumped, is why I mentioned)

Please don't send me PM's for help on BIOS edits, I cannot help with BIOS in PM'sPlease make a thread and I will try to help as soon as I can - thanks!

@Lost_N_BIOSI add nvme module in some dxe but it turned into brick after flashing.Luckly The machine just had one bios chip,so I flashed it back by the spi programmer~I'll try and give you feed back~thanks~

@gloobox - Maybe you picked wrong volume? Or, wrong tool was used? I used UEFITool V25, always check any padding message you get in UEFITool and UEFITool NE, make sure those match before/after mod and even if you do not see these messages. Also, always compare area around microcode volumes (all, by GUID if more than one) and be sure before/after mod the same padding files are above/below microcode or FIT module entries.

Did you check if Intel BootGuard active on this system? If not, that may be why brick too. Check MEInfoWin -verboseThen at end of report, if you see Measured + Verified Boot enabled on left/FPF side, then bootguard probably active so not BIOS mod can be used or = brick.

Please don't send me PM's for help on BIOS edits, I cannot help with BIOS in PM'sPlease make a thread and I will try to help as soon as I can - thanks!